1. Field of the Invention
This invention relates to a harvesting apparatus and, more particularly, to a harvesting apparatus that utilizes pressurized fluid to assist the movement of crop that is cut by the apparatus and/or in a pre-cut state in a field preparatory to processing by the apparatus.
2. Background Art
A basic harvesting system utilizes a combine that separates usable crop from stalks, vines, etc. A wide range of different crops are accumulated and delivered to the combine through a harvesting head. The harvesting heads take different forms based upon the particular crop that is being harvested. Even for the same crop, myriad different designs exist with different operational capabilities.
The heads have different constructions depending upon whether they are designed to sever the crop or handle pre-cut crop. In the former case, cutting may be effected by stationary cutting edges or by edges formed on components that move, as by reciprocation, as the combine is advanced.
In the 1980s, the assignee herein was a pioneer in the design of harvesters utilizing pressurized fluid to assist basic harvester head operation. The state of the art at that time, and one of assignee's early products, are described in U.S. Pat. No. 4,936,082, incorporated herein by reference.
Briefly, pressurized air is directed through stationary drop tubes that work in conjunction with rotary reels to situate crop optimally for severance and advance the severed crop at a continuous and steady flow volume to the combine for further processing thereby. The drop tubes have strategically configured and oriented nozzles to effect this operation.
Alternatively, pressurized fluid is directed through nozzles incorporated into the rotary reel to move therewith to perform the same basic functions.
Harvesting heads may be made with a very substantial width, commonly as high as 45 feet. Designs with widths exceeding 45 feet also exist. Efficient use of the pressurized fluid requires the generation of air streams that collectively produce a curtain that uniformly controls the crop movement across the entire width of the head. To achieve this end, the pressure of the fluid is ideally substantially constant across the entire head width.
Different systems have been devised and are currently in practice with the above design objectives. In one form, two separate fluid pressurizing units are incorporated, each associated with like conduit arrangements that cause the pressurized fluid to advance laterally from opposite sides of the head towards the center, for distribution by the drop tubes or through the rotating reel.
While these systems have been successful commercially, they have a primary drawback that two separate units for generating pressurized fluid must be purchased, incorporated into the heads, and independently operated. The separate units may necessitate a substantial up-front investment. Separate drives are required on the combine for each of the units. This may dictate that a substantial modification be made to a combine to accommodate the separate fluid pressurizing units. Optimal performance requires that the units must be synchronized—a state that may be difficult to establish and maintain. At the same time, two separate units must be incorporated without interfering with other structure or creating an obstruction that must be worked around by the combine operator. Still further, separate units generally require a large power draw which might compromise a combine's ability to operate efficiently and even simultaneously perform other functions for which it is designed. The combine operator is also required to maintain the separate units on a regular basis.
It is known to use a single source of pressurized fluid to deliver a fluid by movement thereof in a single direction through the entire length of a manifold with associated drop tubes along the widthwise extent thereof. Regardless of the capacity of this type of pressurized fluid source, there inevitably results a significant variation in pressure of fluid discharging from the drop tube nozzles along the head width. This can lead to uneven crop delivery and/or localized accumulation that may interfere with efficient combine operation and in the end result in loss of valuable, usable crop. Typically, baffles are incorporated into the manifold and/or the cross-sectional area thereof may be strategically reduced to maintain pressure. However, typically there will still be a localized pressure reduction around the baffle that may compromise overall system performance.
Another problem that has plagued the industry is the unwanted accumulation of crop at the rear of the frame at a feed housing on the frame through which accumulated crop is directed for delivery to a combine for processing thereby. This accumulation may progressively increase to the point that it interferes with a desired steady volume of flow of crop from the head to the combine. Manual clearing of this accumulation of crop may be required. This results in an interruption of the harvesting operation and also is burdensome to the combine operator. This crop accumulation could also interfere with the operator's visual monitoring of the head as the combine is advanced.
In spite of the above problems, the industry has continued to use the above-described systems since alternative designs that would alleviate the above problems have not heretofore been devised.